Optical Engineering

Developing wideband stable platforms for tracking and pointing systems is often inhibited by plants containing high-order dynamics and nonlinearities. Control system stability and robustness are commonly achieved by using passive compensators to frequency shape the active state variables. In the presence of nonlinearities and high-order dynamics, fixed frequency, passive parameter compensators usually lead to overly complex solutions. In such systems, however, control stability can be achieved by manipulating the active state variables themselves. The general concepts of state equalization, a control system stabilization technique that utilizes the differing characteristics of the active state variables to achieve the desired stability in systems containing nonlinear resonant plants, is presented. The resonance phenomenon and state variable relationships in resonance are discussed and analytical models are presented. An existing application is used to illustrate the use of state equalization in extending rate loop bandwidth.